Python中实现高效的列表过滤多种方法示例

# 示例列表
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# 使用 for 循环过滤出偶数
filtered_numbers = []
for number in numbers:
    if number % 2 == 0:
        filtered_numbers.append(number)

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

# 使用列表推导式过滤出偶数
filtered_numbers = [number for number in numbers if number % 2 == 0]

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

# 使用 filter 函数过滤出偶数
filtered_numbers = list(filter(lambda x: x % 2 == 0, numbers))

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

import itertools

# 使用 itertools.filterfalse 过滤出偶数
from itertools import filterfalse

filtered_numbers = list(filterfalse(lambda x: x % 2 != 0, numbers))

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

import pandas as pd

# 创建一个 pandas Series
numbers_series = pd.Series(numbers)

# 使用 pandas 过滤出偶数
filtered_numbers = numbers_series[numbers_series % 2 == 0].tolist()

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

import numpy as np

# 创建一个 numpy 数组
numbers_array = np.array(numbers)

# 使用 numpy 过滤出偶数
filtered_numbers = numbers_array[numbers_array % 2 == 0].tolist()

print(filtered_numbers)  # 输出: [2, 4, 6, 8, 10]

# 使用生成器表达式过滤出偶数
filtered_numbers = (number for number in numbers if number % 2 == 0)

for num in filtered_numbers:
    print(num)  # 输出: 2, 4, 6, 8, 10

import timeit

setup_code = '''
numbers = list(range(1, 1000000))
'''

# for 循环
time_for_loop = timeit.timeit('''
filtered_numbers = []
for number in numbers:
    if number % 2 == 0:
        filtered_numbers.append(number)
''', setup=setup_code, number=10)

# 列表推导式
time_list_comp = timeit.timeit('''
filtered_numbers = [number for number in numbers if number % 2 == 0]
''', setup=setup_code, number=10)

# filter 函数
time_filter_func = timeit.timeit('''
filtered_numbers = list(filter(lambda x: x % 2 == 0, numbers))
''', setup=setup_code, number=10)

print(f'For 循环耗时: {time_for_loop}')
print(f'列表推导式耗时: {time_list_comp}')
print(f'Filter 函数耗时: {time_filter_func}')

nested_list = [[1, 6], [3, 7], [5, 8], [2, 9]]

# 使用列表推导式处理嵌套列表
filtered_numbers = [num for sublist in nested_list for num in sublist if num > 5]

print(filtered_numbers)  # 输出: [6, 7, 8, 9]

users = [
    {'name': 'Alice', 'age': 25},
    {'name': 'Bob', 'age': 35},
    {'name': 'Charlie', 'age': 30},
    {'name': 'David', 'age': 40}
]

# 使用列表推导式过滤
filtered_users = [user for user in users if user['age'] > 30]

print(filtered_users)
# 输出: [{'name': 'Bob', 'age': 35}, {'name': 'David', 'age': 40}]